K-27 submarine reactor accident, 1968

compiled by Wm. Robert Johnston
last modified 20 September 2007

Date:
24 May 1968

Location:
Barents Sea, aboard K-27 submarine

Type of event:
reactor coolant leak and partial meltdown

Description:

A reactor accident occurred aboard the submarine K-27. The K-27, launched 1 April 1962 and commissioned 30 October 1963, was the sole Project 645 (November-ZhMT) class submarine; it had two liquid metal (lead-bismuth) cooled reactors each with a capacity of 73 MWt. The system tended to leak steam that would oxidize the liquid metal coolant, requiring frequent cleaning of oxide particles from the coolant. In May 1968 submarine K-27 was ordered to participate in a naval exercise, despite objections that the reactor coolant was due for cleaning. On 24 May, K-27 was sailing at full power when the port reactor dropped to 7% power due to a coolant failure. Probably the buildup of oxide particles had prevented coolant flow to one part of the reactor, causing it to overheat such that some fuel melted. Fission products leaked into the reactor compartment and eventually to the rest of the submarine. The submarine used the starboard reactor to return to port. Radiation exposures to the crew caused 9 deaths and 83 injuries, including 40 with acute radiation sickness. Efforts to repair the submarine were unsuccessful, and the whole submarine was scuttled in Stepovogo Bay at Novaya Zemlya in 1981.